Rotary toothbrush



Dec 22,1942. F, G, HART 2,306,264 ,IYAROTARY TooTHBRUsH I Filed March 1o, 1941 A Trae/vir Patented Dec. 22, 1942 UNETED STAT itali-NT FFICE 7 Claims.

The present invention relates to a rotary tooth brush and particularly to a brush so constructed that it can readily adapt itself to the curvatures of the rows cf teeth and to the varying thicknesses of the teeth.

In prior devices of this character, opposed rotary brushes have been used for simultaneous engagement with opposite sides of the teeth, such a device being shown, for example, in Eisner et al., Patent No. 1,338,821, dated May 4, 1920. An outstanding difculty with all prior opposed rotary brushes of this character is their inability to accommodate themselves to the varying thicknesses and surface irregularities of the teeth.

My invention contemplates a, rotary tooth brush of `such construction that the difficulties above outlined may be overcome. One feature of the invention resides in an arrangement of the opposed rotary brushes that enables portions of at least one olf them to move yiel-dingly away from the other in accommodating the relatively thick back teeth, but to be automatically restored to normal position for simultaneous engagement with the opposite sides of the thinner front teeth.

Other and further objects and advantages of the invention will hereinafter more fully appear from the following detailed description taken in connection with the accompanying drawing, in which- Fig. l is a side elevation of a tooth brush embodying the invention.

Fig. 2 is a sectional ,view on a larger scale through the brush.

Fig. 3 is an elevation of the brush looking in the direction of the arrow 3 of Fig l.

Fig. 4 is a fragmentary sectional view similar to Fig. 2 and showing a modication.

Fig. 5 shows Jthe brush engaging with the teeth.

As shown in Figs. l and 2, my improved rotary tooth brush includes a suitable handle I which terminates in a relatively flat circular portion la, the latter on its inner surface having a circular recess lb which is substantially surrounded by an overhanging flange or guard lc, for a, purpose to be hereinafter more fully described. Projecting centrally froml and at right angles to this recessed face of handle l is a short stub shaft 2, the latter, as shown in Fig. 2, having a terminal enlargement 2a firmly embedded in the material of the handle to provide a rigid mounting for said stub shaft. This stub shaft 2 provides rotative support, in a manner to be hereinafter described, for both of my opposed brushes, designated in the drawing by the numerals 3 and 4-these two brushes forming part of an assembly which is rotatable on the stub shaft 2 and-is removable as a unit therefrom.

As .shown in Fig. 2, the inner member of this brush assembly is a short bushing 5, adapted to ht over and rotate upon the Vstub shaft 2 and having a flange 5a at the end thereof arranged when the brush assembly is in place, to receive interiorly suitable snap rings 6 which engage in a groove 'i in the stub shaft 2, thereby to releasably retain the rotary brush assembly in position.

According to my invention, the brushes 3 and Il are assembled on the bushing 45 so as to rotate in unison with said bushing; the `assembly and connection of the parts is of a resilient character such as to .permit one of saidbrushes duringrotation to deflect and to loccupyplanes of rotation lat are out of parallel with the plane of rotation of the other brush. Thisflexibility of connection between the brushes ;3 and 4 is obtainable in a variety of wayspbne simpleiand convenient way, as herein illustrated, ,is to employ an elongated relatively-flexible hub member 9, of

rubber or the like, for the support of the brush.

il in overhanging relation to the stub shaft 2 and bushing 5. As shown in Fig. 2, said rubber hub at its other end is recessed and internally threaded, so'that it can be yscrewed,`onto .the external threads 8 of bushing 5. .This attachment of hub 9 to bushing 5 is preferably utilized to secure the other brush 3 in position on the bushing; said other brush 3 comprises, as shown, an annular dished backing member 3a having bristles 3b embedded in and extendinginga ring from one side thereof. Centrally of thefmember .3a is an Vopening lil to receive the bushing, and the surfaces `of the said .member centrally thereof, around the opening lil, are free from bristles so that said member may be clamped securely between a shoulder H formed by flange 5a of bushing 5 and the end of the hub 9 as the latter is screwed down tightly against the member 3a.

By virtue of the fact that brush 4, opposing the brush 3, is mounted o-n the free overhanging end of flexible hub ti, said brush 4, when rotating. in unison with brush 3, is susceptible of deflection from the normal position shown by Fig. 2, into a position where its plane of rotation is more or less out of parallel with the plane of rotation of brush 3; this deflection, occurring when the brushes encounter the larger thicker back teeth (as shown in Fig. 5), is permitted by the flexibility of the member 9 on which said brush 4 is supported.

In order to obtain this deflection even more readily and also to avoid undue crowding together of the opposed bristles in the zone I6, Fig. 5, the brush 4 is preferably made up of a plurality of segments 4a, 4a, as shown in Fig. 3. Each segment 4a comprises a wedge-shaped backing element 4b with bristles 4c projecting from one side thereof. Each backing element 4a adjacent the point of the wedge has a tongue I2 engageable with a, recess I3 in the end of the hub 9. 'I'he several recesses I2 for the several segments of the brush 4 are uniformly spaced about the end of the hub 9 so that, when the segments are in position on the hub 9, the several segments will present the bristles in opposed relation to the bristles of the brush 3 and in a substantially continuous ring.

As shown in Fig. 2, the hub 9 is provided with a central recess I3 inside of the group of recesses I2 to increase the flexibility of the hub at its outer end so that, when the brush is in use, any one of the segments of the brush 4 may move away from the opposed portion of the brush 3, as shown for example in Fig. 5, so that the brushes will readily accommodate the relatively thick back teeth.

In use, the rbrushes are positioned on the teeth as shown in Fig. 5 and moved in a direction parallel to the row of teeth. By this movement the brushes are caused to rotate and thereby effect a thorough cleaning action on the opposed surfaces of the teeth. As the teeth become less thick toward the front of the users mouth, the resiliency of the hub 9 restores the segments of the brush 4 to the normal position of Fig. 2 for engagement with opposed sides of the thinner teeth at the front of the mouth. 'Ihe rubber hub 9, as shown in Figs. 2 and 5, engages with the edges or grinding surfaces of the teeth, and assures rotation of the brushes as same are moved length- Wise of the row of teeth. The device is preferably used on each row of teeth separately as is indicated in Fig. 5, where the device is shown in engagement only with one row of teeth. As so used, on either the upper teeth or the lower teeth, the overhanging flange Ic of handle I serves as an effective guard for the users lip, which, in the operation of the device, is in the approximate position indicated at I1, Fig. 5.

With reference now to Fig. 4, the resiliency of the hub may be materially increased for holding the brushes more securely against the teeth surfaces. As shown, the hub 9' has the recess I3 to receive the tongues I2 on the segments of the brush 4 and a spring I5, preferably of helical formation, is embedded Within the rubber hub to surround the centrally located recess I4.

It will be understood that tooth brushes of this character may be readily kept in a clean and sterile condition, since the brush as a unit may be withdrawn from the handle, or if necessary, the entire brush may be taken to pieces for thorough cleaning and sterilizing.

I claim:

1. In a tooth brush, a handle and a pair of opposed annular brushes rotatably mounted on said handle adjacent one end thereof, one of said brushes being in sections, with each section individually resiliently mounted for movement of the individual sections relative to each other and to the other brush.

2. In a tooth brush, a handle having a spindle adjacent one end thereof, a hubrotatable on said spindle and supporting a pair of opposed annular brushes, said hub being resilient for relative movement between the brushes.

3. In a tooth brush, a handle having a spindle adjacent one end thereof, a resilient hub rotatable on said spindle and supporting a pair of opposed annular brushes, one of said brushes being segmental and supported adjacent the outer end of the hub, the resiliency of the hub permitting individual movement of the segments of the brush relative to the other brush.

4. In a tooth brush, a handle having a spindle adjacent one end thereof, a hub rotatable on said spindle and supporting a pair of opposed annular brushes, one of said brushes being segmental and supported adjacent the outer end of the hub, said hub being resilient and having a central recess in the outer end thereof to increase its resiliency, providing for a movement of the parts of the segmental brush relative to the other brush.

5. In a tooth brush of the class described, a pair of opposed brushes connected and supported for rotation in unison, one of said brushes having a mounting which is ilexible transversely, to permit deflection of said brush into a plane of rotation which is out of parallel with the plane of rotation of the other brush.

6. In a tooth brush of the class described, a pair of opposed brushes adapted for rotation in unison, means for rigidly supporting one of said brushes and means for yieldably` supporting the other brush, whereby the latter can deflect into a. plane of rotation out of parallel with the plane of rotation of the rst brush.

7. In a tooth brush of the class described, a handle, a shaft projecting therefrom, and a pair of opposed brushes rotatable together on the axis provided by said shaft, the means connecting said brushes being a member of flexible material, having a portion overhanging said shaft, and to which portion one of said brushes is secured.

FENN G. HART. 

